1. Field of the Invention
The invention relates to shuttleless looms wherein weft yarn is supplied from a stationary source and is inserted into sheds of warp threads by opposed carrier members that are attached to the free end of flexible tapes which are alternately wrapped about and extended from oscillating tape wheels located at each side of the loom. In timed sequence with the weaving cycle the weft yarn is acted upon by a presenting member which locates the weft in a position for reception by a so-called inserting carrier which carries said weft into the shed and presents it to a so-called extending carrier that draws the weft through the remainder of the shed to complete a single pick. In particular the invention pertains to an improved device for assuring positive positioning of the weft for reception into the inserting carrier by tensioning and preventing the development of slack in said weft in the area adjacent the edge of the fabric being formed.
2. Description of the Prior Art
Shuttleless looms to which the present invention is applicable can be of the type in which weft is supplied from one or more sources or which may employ either the Gabler or Dewas system of weft insertion. In such looms, a weft presenting member is actuated in timed sequence with the weaving cycle so as to locate said weft in a position where it will be received into and taken by the inserting carrier into a shed for presentation to the weft extending carrier.
Spring biased disc-type yarn tensioning devices are well known and have been utilized on shuttleless looms as well as vertically disposed spring biased friction plates such as shown and described in U.S. Pat. No. 3,561,488. These known types of tensioning devices are fixed on the loom and located intermediate the weft presenting member or members and the source or sources of weft supply. The known forms of weft tensioning devices have not been completely satisfactory in maintaining a positive tension on the weft in the area intermediate said devices and the edge of the fabric being formed. Relative to this particular area, many complaints were received on loss of tension and the development of slack in the weft which in many cases was sufficient to prevent the presenting member from properly locating the weft for reception by the inserting carrier. With the development of slack in the weft in the area intermediate the tensioning device and the fabric edge there is no way to recover the lost tension and will result in a cessation of loom operation due to lack of weft. The development of slack in the weft as described above can be caused in a number of ways such as dancing or linear movement of the presenting member which will actually withdraw a slight amount of weft from its source and when attempting to locate said weft for reception by the inserting carrier the slackness therein will cause the weft to be lowered beyond the carrier pick-up position. Vibration of the various loom elements during loom operation has frequently been responsible for loss of tension of the weft. Overhead air cleaners for removing lint from a loom have caused loss of tension on certain types of weft yarns which must be withdrawn from their source under a minimum amount of tension due to the strength thereof and the type of fabric being woven. Another cause of loss of tension to the weft is movement of the lay beam during beat-up of a pick which will actually pull a slight amount of weft through the tensioning device and create enough slack therein so as to effect a change in the position in which the presenting member places it for pick-up by the inserting carrier. It is very important that the weft yarn be precisely located when presented to the inserting carrier for the weft pick range of the latter is quite narrow and a small deviation in this position frequently results in failure to insert the intended pick.
A still further cause for loss of weft tension is the build-up of lint or other foreign matter between the spring biased elements through which the weft passes and which are intended to tension said weft.
The weft control device of the present invention has overcome the problems described above by providing a weft control device of the self-cleaning type which applies and maintains a predetermined amount of tension to the weft and assures positive positioning of the latter for presentation to the inserting carrier.